These mirror
screws were made by Bell Labs around 1933 for television experiments.
They were donated by the estate of Robert Eilenberger, who was a Bell
Labs engineer from 1941 to 1982, working primarily on development of the Picturephone. We will have more on his career posted later.
Here are Bell Labs pictures from Bob
Eilenberger's collection.

(click on picture for high resolution image)

These screws are for a 60 line picture. Notice the very small size of the
one on the right. It produced a picture only about 1 x 1 inch.

This picture, also from Mr. Eilenberger's estate, shows a Bell Labs dual
mirror screw receiver made in 1933. These screws are not the same ones in
our collection. Since two screws are used, it is possible that this
device was for a Picturephone experiment, one for the camera and one for
the receiver.